## Improving security in the cloud

Cloud computing will keep increasing as the demand for computing power increases.

That increase also raises some crucial questions about security like can a user perform computations on data stored in “the cloud” without letting anyone else see the information?

There will soon be the capability to work on data while it is still undergoing encryption, giving an encrypted result that a user can later securely decipher, according to research at the Weizmann Institute and MIT.

Cloud computing is simply an operation carried out on a network of shared, remote servers and the idea of securing the cloud has been an issue in the industry for quite a while.

Attempting computation on sensitive data stored on shared servers leaves that data exposed in ways that traditional encryption techniques can’t protect against.

The main problem is that to manipulate the data, you first have to decode it. “Until a few years ago, no one knew if the encryption needed for this sort of online security was even possible,” said Dr. Zvika Brakerski, who just completed his PhD in the group of Professor Shafi Goldwasser of the Computer Science and Applied Mathematics Dept. at Weizmann.

In 2009, however, Craig Gentry, a PhD student at Stanford University, provided the first demonstration of fully homomorphic encryption (FHE). But the original method was extraordinarily time consuming and unwieldy, making it highly impractical. Gentry constructed his FHE system by using fairly sophisticated math, based on ideal lattices, and this required him to make new and unfamiliar complexity assumptions to prove security.

Gentry’s use of ideal lattices seemed inherent to fully homomorphic encryption; researchers assumed they were necessary for the server to perform such basic operations as addition and multiplication on encrypted data.

Brakerski, together with Dr. Vinod Vaikuntanathan (who was a student of Goldwasser’s at MIT), surprised the computer security world earlier this year with two papers describing several new ways of making fully homomorphic encryption more efficient.

For one, they managed to make FHE work with much simpler arithmetic, which speeds up processing time. And a surprise discovery showed a mathematical construct used to generate the encryption keys could be more simple without compromising security. Gentry’s original ideal lattices are theoretical collections of points that can add together – as in an ordinary lattice structure – but also multiplied. But the new research shows the lattice does not have to be ideal, which simplifies the construction immensely. “The fact that it worked was something like magic, and it has challenged our assumptions about the function of the ideal lattices in homomorphic encryption,” Brakerski said.

Their result promises to pave a path to applying FHE in practice. Optimized versions of the new system could be hundreds – or even thousands of times faster than Gentry’s original construction.

Indeed, Brakerski and Vaikuntanathan have managed to advance the theory behind fully homomorphic encryption to the point that computer engineers can begin to work on applications.